Fuel cell system and method of detecting abnormality of fuel cell system

Abstract

A fuel cell system and an abnormality detecting method therefore is provided. The fuel cell system includes: a fuel cell that includes at least one fuel-cell cell having an anode, a cathode and an electrolyte membrane, an anode-side passage supplying and exhausting fuel gas to and from the anode, a cathode-side passage supplying and exhausting oxidation gas to and from the cathode, a voltage detecting unit detecting a fuel cell voltage, a suppressing unit setting a suppression state where, after terminating normal power generation, introduction of the fuel and oxidation gas to the anode-side and cathode-side passages and emission of the fuel and oxidation gas from the anode-side and cathode-side passages to outsides are suppressed as compared with those during the normal power generation; and an abnormality detecting unit, after setting the suppression state, detecting abnormality of the fuel cell system based on the detected voltage or a variation thereof.

The invention claimed is: 
     
       1. A fuel cell system comprising:
 a fuel cell that includes at least one fuel-cell cell having an anode, a cathode and an electrolyte membrane; 
 an anode-side passage adapted to supply and exhaust fuel gas to and from the anode of the at least one fuel-cell cell; 
 a cathode-side passage adapted to supply and exhaust oxidation gas to and from the cathode of the at least one fuel-cell cell; 
 a voltage detecting unit adapted to detect a voltage of the fuel cell; 
 a suppressing unit adapted to set a suppression state where, after normal power generation of the fuel cell is terminated, introduction of the fuel gas to the anode-side passage and introduction of the oxidation gas to the cathode-side passage are suppressed as compared with those during the normal power generation, and emission of the fuel gas from the anode-side passage to an outside of the anode-side passage and emission of the oxidation gas from the cathode-side passage to an outside of the cathode-side passage are suppressed as compared with those during the normal power generation; 
 an abnormality detecting unit comprising a controller that is programmed to detect, after the suppression state is set by the suppressing unit, abnormality of the fuel cell system on the basis of the voltage detected by the voltage detecting unit or a variation in the detected voltage, and 
 a voltage variation detecting unit adapted to detect a voltage variation, which is real number value, per unit time at a predetermined time interval on the basis of the voltage detected by the voltage detecting unit, wherein 
 the abnormality detecting unit comprising the controller is programmed to detect, that the fuel cell system is abnormal when a period of time that elapses from when the suppression state is set to when the voltage variation detected by the voltage variation detecting unit becomes a third voltage variation determination value, which is larger than or equal to zero, is shorter than a first time determination value. 
 
     
     
       2. A fuel cell system comprising:
 a fuel cell that includes at least one fuel-cell cell having an anode, a cathode and an electrolyte membrane; 
 an anode-side passage adapted to supply and exhaust fuel gas to and from the anode of the at least one fuel-cell cell; 
 a cathode-side passage adapted to supply and exhaust oxidation gas to and from the cathode of the at least one fuel-cell cell; 
 a voltage detecting unit adapted to detect a voltage of the fuel cell; 
 a suppressing unit adapted to set a suppression state where, after normal power generation of the fuel cell is terminated, introduction of the fuel gas to the anode-side passage and introduction of the oxidation gas to the cathode-side passage are suppressed as compared with those during the normal power generation, and emission of the fuel gas from the anode-side passage to an outside of the anode-side passage and emission of the oxidation gas from the cathode-side passage to an outside of the cathode-side passage are suppressed as compared with those during the normal power generation; 
 an abnormality detecting unit comprising a controller that is programmed to detect, after the suppression state is set by the suppressing unit, abnormality of the fuel cell system on the basis of the voltage detected by the voltage detecting unit or a variation in the detected voltage, and 
 a voltage variation detecting unit adapted to detect a voltage variation, which is real number value, per unit time at a predetermined time interval, wherein 
 the abnormality detecting unit comprising the controller is programmed to detect that the fuel cell system is abnormal when, after the suppression state is set, the voltage variation detected by the voltage variation detecting unit becomes larger than a fourth voltage variation determination value, which is larger than or equal to zero, the voltage detected by the voltage detecting unit becomes higher than a second voltage determination value, which is higher than or equal to zero, and then the voltage decreases to become lower than a third voltage determination value, and when a period of time that elapses from when the voltage becomes higher than the second voltage determination value to when the voltage becomes lower than the third voltage determination value is shorter than a second time determination value. 
 
     
     
       3. The fuel cell system according to  claim 1 , wherein
 the abnormality detecting unit comprising the controller is programmed to detect that the fuel cell system is abnormal when, after the suppression state is set, the voltage variation detected by the voltage variation detecting unit becomes larger than a fifth voltage variation determination value, which is larger than or equal to zero, and the voltage variation becomes approximately zero and then the voltage detected by the voltage detecting unit becomes lower than a fourth voltage determination value, which is higher than or equal to zero, and when a period of time that elapses from when the voltage variation becomes larger than the fifth voltage variation determination value to when the voltage becomes smaller than the fourth voltage determination value is shorter than a third time determination value, which is longer than or equal to zero. 
 
     
     
       4. The fuel cell system according to  claim 1 , wherein
 the abnormality detecting unit comprising the controller is programmed to detect that the fuel cell system is abnormal when, after the suppression state is set, the voltage variation detected by the voltage variation detecting unit becomes larger than a sixth voltage variation determination value, which is larger than or equal to zero, and then the voltage variation becomes approximately zero, and when a period of time that elapses from when the voltage variation becomes larger than the sixth voltage variation determination value to when the voltage variation becomes approximately zero is shorter than a fourth time determination value. 
 
     
     
       5. The fuel cell system according to  claim 1 , wherein
 the abnormality detecting unit comprising the controller is programmed to execute abnormality detection of the fuel cell system based on the variation in the voltage when the amount of the fuel gas in the anode-side passage is larger than a first amount determination value. 
 
     
     
       6. The fuel cell system according to  claim 1 , wherein
 when the amount of the fuel gas in the anode-side passage is smaller than a second amount determination value, the abnormality detecting unit comprising the controller is programmed to detect that the fuel cell system is abnormal when a period of time that elapses from when the suppression state is set to when the voltage detected by the voltage detecting unit becomes lower than a fourth voltage determination value, which is higher than or equal to zero, is longer than a fifth time determination value. 
 
     
     
       7. The fuel cell system according to  claim 1 , wherein
 when the abnormality of the fuel cell is detected, the abnormality detecting unit comprising the controller is programmed to not use the variation in the voltage detected by the voltage detecting unit during a predetermined period of time after the suppression state is set. 
 
     
     
       8. The fuel cell system according to  claim 1 , further comprising:
 a connecting unit adapted to connect an electrical load to the fuel cell for a predetermined period of time after the normal power generation in the fuel cell is terminated and before the suppressing unit sets the suppression state. 
 
     
     
       9. The fuel cell system according to  claim 1 , wherein
 the suppressing unit includes an anode-side emission suppressing valve that is arranged in the anode-side passage and that is adapted to suppress emission of fuel gas, which has been subjected to electrochemical reaction, from the anode of the at least one fuel-cell cell to an outside of the fuel cell, wherein the suppression state includes a state where the anode-side emission suppressing valve is closed. 
 
     
     
       10. The fuel cell system according to  claim 1 , wherein
 the suppressing unit includes an oxidation gas supply pump that is arranged in the cathode-side passage and that is adapted to supply oxidation gas to the cathode of the at least one fuel-cell cell, wherein the suppression state includes a state where the oxidation gas supply pump is stopped. 
 
     
     
       11. The fuel cell system according to  claim 1 , wherein
 the suppressing unit includes a fuel gas shut-off valve that is arranged in the anode-side passage and that is able to shut off supply of the fuel gas to the anode of the at least one fuel-cell cell, wherein the suppression state includes a state where the fuel gas shut-off valve is closed. 
 
     
     
       12. The fuel cell system according to  claim 1 , wherein
 the suppressing unit includes a cathode-side emission suppressing valve that is arranged in the cathode-side passage and that is adapted to suppress emission of oxidation gas, which has been subjected to electrochemical reaction, from the cathode of the at least one fuel-cell cell, to an outside of the fuel cell, wherein the suppression state includes a state where the cathode-side emission suppressing valve is closed. 
 
     
     
       13. The fuel cell system according to  claim 1 , wherein
 the fuel cell includes a fuel cell stack formed of a plurality of the fuel-cell cells, 
 the cathode-side passage includes an oxidation gas exhaust manifold that extends through the fuel cell stack in a stacking direction in which the fuel-cell cells are stacked and that is adapted to collect and exhaust oxidation gas, which has been subjected to electrochemical reaction in the cathode of each of the fuel-cell cells, and an oxidation gas emission passage that is connected to the oxidation gas exhaust manifold on a side surface of the fuel cell stack for emitting the oxidation gas, exhausted from the oxidation gas exhaust manifold, to an outside of the cathode-side passage, 
 the suppressing unit includes a cathode-side emission suppressing valve that is arranged in the oxidation gas emission passage and that suppresses emission of the oxidation gas to an outside of the fuel cell and a sealing portion that is adapted to suppress, in each fuel-cell cell, leakage of the oxidation gas from the cathode to an outside of the fuel-cell cell, 
 the voltage detecting unit is adapted to measure voltages of fuel-cell cell groups, each of which is formed of one or more of the fuel-cell cells, in the fuel cell stack, and 
 the abnormality detecting unit comprising the controller is programmed to detect abnormality of the cathode-side emission suppressing valve or abnormality of the sealing portion on the basis of the voltages of the fuel-cell cell groups detected by the voltage detecting unit or the variations in the detected voltages. 
 
     
     
       14. The fuel cell system according to  claim 13 , wherein
 the abnormality detecting unit comprising the controller is programmed to detect that the cathode-side emission suppressing valve is abnormal when the voltage of the fuel-cell cell group adjacent to the side surface of the fuel cell stack becomes higher than the voltages of the other fuel-cell cell groups and becomes higher than a fifth voltage determination value. 
 
     
     
       15. The fuel cell system according to  claim 13 ; wherein
 when, among predetermined fuel-cell cell groups other than the fuel-cell cell group adjacent to the side surface of the fuel cell stack, a high-voltage fuel-cell cell group, of which the voltage becomes higher than the fuel-cell cell group adjacent to the side surface of the fuel cell stack, appears, and the voltage of the high-voltage fuel-cell cell group becomes higher than a sixth voltage determination value, the abnormality detecting unit comprising the controller is programmed to detect that the sealing portion in the high-voltage fuel-cell cell group is abnormal. 
 
     
     
       16. The fuel cell system according to  claim 1 , wherein
 the abnormality detecting unit further comprises a notification unit that is configured to notify the abnormality when the abnormality is detected. 
 
     
     
       17. The fuel cell system according to  claim 2 , wherein
 the abnormality detecting unit comprising the controller is programmed to execute abnormality detection of the fuel cell system based on the variation in the voltage when the amount of the fuel gas in the anode-side passage is larger than a first amount determination value. 
 
     
     
       18. The fuel cell system according to  claim 2 , wherein
 when the amount of the fuel gas in the anode-side passage is smaller than a second amount determination value, the abnormality detecting unit comprising the controller is programmed to detect that the fuel cell system is abnormal when a period of time that elapses from when the suppression state is set to when the voltage detected by the voltage detecting unit becomes lower than a fourth voltage determination value, which is higher than or equal to zero, is longer than a fifth time determination value. 
 
     
     
       19. The fuel cell system according to  claim 2 , wherein
 when the abnormality of the fuel cell is detected, the abnormality detecting unit comprising the controller is programmed to not use the variation in the voltage detected by the voltage detecting unit during a predetermined period of time after the suppression state is set. 
 
     
     
       20. The fuel cell system according to  claim 2 , further comprising:
 a connecting unit adapted to connect an electrical load to the fuel cell for a predetermined period of time after the normal power generation in the fuel cell is terminated and before the suppressing unit sets the suppression state. 
 
     
     
       21. The fuel cell system according to  claim 2 , wherein
 the suppressing unit includes an anode-side emission suppressing valve that is arranged in the anode-side passage and that adapted to suppress emission of fuel gas, which has been subjected to electrochemical reaction, from the anode of the at least one fuel-cell cell to an outside of the fuel cell, wherein the suppression state includes a state where the anode-side emission suppressing valve is closed. 
 
     
     
       22. The fuel cell system according to  claim 2 , wherein
 the suppressing unit includes an oxidation gas supply pump that is arranged in the cathode-side passage and that is adapted to supply oxidation gas to the cathode of the at least one fuel-cell cell, wherein the suppression state includes a state where the oxidation gas supply pump is stopped. 
 
     
     
       23. The fuel cell system according to  claim 2 , wherein
 the suppressing unit includes a fuel gas shut-off valve that is arranged in the anode-side passage and that is able to shut off supply of the fuel gas to the anode of the at least one fuel-cell cell, wherein the suppression state includes a state where the fuel gas shut-off valve is closed. 
 
     
     
       24. The fuel cell system according to  claim 2 , wherein
 the suppressing unit includes a cathode-side emission suppressing valve that is arranged in the cathode-side passage and that is adapted to suppress emission of oxidation gas, which has been subjected to electrochemical reaction, from the cathode of the at least one fuel-cell cell, to an outside of the fuel cell, wherein the suppression state includes a state where the cathode-side emission suppressing valve is closed. 
 
     
     
       25. The fuel cell system according to  claim 2 , wherein
 the fuel cell includes a fuel cell stack formed of a plurality of the fuel-cell cells, 
 the cathode-side passage includes an oxidation gas exhaust manifold that extends through the fuel cell stack in a stacking direction in which the fuel-cell cells are stacked and that is adapted to collect and exhaust oxidation gas, which has been subjected to electrochemical reaction in the cathode of each of the fuel-cell cells, and an oxidation gas emission passage that is connected to the oxidation gas exhaust manifold on a side surface of the fuel cell stack for emitting the oxidation gas, exhausted from the oxidation gas exhaust manifold, to an outside of the cathode-side passage, 
 the suppressing unit includes a cathode-side emission suppressing valve that is arranged in the oxidation gas emission passage and that suppresses emission of the oxidation gas to an outside of the fuel cell and a sealing portion that is adapted to suppress, in each fuel-cell cell, leakage of the oxidation gas from the cathode to an outside of the fuel-cell cell, 
 the voltage detecting unit is adapted to measure voltages of fuel-cell cell groups, each of which is formed of one or more of the fuel-cell cells, in the fuel cell stack, and 
 the abnormality detecting unit comprising the controller is programmed to detect abnormality of the cathode-side emission suppressing valve or abnormality of the sealing portion on the basis of the voltages of the fuel-cell cell groups detected by the voltage detecting unit or the variations in the detected voltages. 
 
     
     
       26. The fuel cell system according to  claim 25 , wherein
 the abnormality detecting unit comprising the controller is programmed to detect that the cathode-side emission suppressing valve is abnormal when the voltage of the fuel-cell cell group adjacent to the side surface of the fuel cell stack becomes higher than the voltages of the other fuel-cell cell groups and becomes higher than a fifth voltage determination value. 
 
     
     
       27. The fuel cell system according to  claim 25 , wherein
 when, among predetermined fuel-cell cell groups other than the fuel-cell cell group adjacent to the side surface of the fuel cell stack, a high-voltage fuel-cell cell group, of which the voltage becomes higher than the fuel-cell cell group adjacent to the side surface of the fuel cell stack, appears, and the voltage of the high-voltage fuel-cell cell group becomes higher than a sixth voltage determination value, the abnormality detecting unit comprising the controller is programmed to detect that the sealing portion in the high-voltage fuel-cell cell group is abnormal. 
 
     
     
       28. The fuel cell system according to  claim 2 , wherein
 the abnormality detecting unit further comprises a notification unit that is configured to notify the abnormality when the abnormality is detected.